The proposed research is an in vitro study of wound contraction inhibition by certain well-characterized collagen-GAG (CG) matrices. A small class of these highly porous CG matrices have significantly delayed in vivo contraction and induced regeneration of a physiologic dermis in a rodent model in which the dermis does not regenerate spontaneously. Evidence suggests that inhibition of contraction is necessary for regeneration. An in vitro model consisting of fibroblast-populated porous CG matrices will be used to study the effects of carefully controlled extracellular matrix environments upon fibroblast behavior. The relationship between ECM receptor utilization (integrins), fibroblast activity (migration vs. contraction), and collagen topography (loose fibrils vs. densely packed collagen surfaces) will be established. Changes in integrin receptor utilization as determined by immunolocalization before and after the onset of contraction will be determined by light and electron microscopy. Immunoelectron microscopy will be used to co-localize specific integrin receptors to actin cytoskeletal elements of contractile fibroblasts in order to correlate receptor utilization to microfilament reorganization and collagen topography. This will test the hypothesis that porous CG matrices influence the utilization of receptors and the organization of cytoskeletal elements of fibroblasts thus controlling activities of migration and contraction. The effects of fibroblast mediated contraction and porous CG matrix architecture upon newly synthesized collagen fibril bundle organization will also be studied in long-term cultures supplemented with ascorbic acid. The degree of fibroblast contraction of porous CG matrices and the architecture of CG matrices will be independently varied in order to study their separate roles in collagen fiber bundle organization. This will allow determination of whether CG matrix alters the basic organization of newly synthesized connective tissue and whether the mechanical stress of wound contraction is the primary factor in aligning and compacting collagen fiber bundles into scar tissue. The effect of CG matrix upon the responsiveness of fibroblasts to growth factors known to increase collagen synthesis will also be determined. These are basic studies which will elucidate the molecular mechanism by which CG matrices inhibit contraction and the roles of contraction and CG matrix architecture upon organization of collagen fiber bundles in newly formed tissue. These studies will improve the understanding of the effects of cell-matrix interactions in normal wound healing events and in connective tissue regeneration.